Class DictionaryBinarySearch

java.lang.Object

DictionaryBinarySearch

public abstract class DictionaryBinarySearch
extends java.lang.Object

A custom variant of binary search used for the steganography dictionaries which handles searching a multi-language dictionary where the data is "almost" sorted, as there are some words with different accents, etc. from other languages which cause it not to be sorted properly. Currently only handles Germanic, and Romance based languages such as English, French, German, Spanish (anything that is latin character based)

Field Summary

Fields

Modifier and Type	Field and Description
private static int	DIVERGENT_SEARCH_STEPS The number of steps to take when performing the divergent search, if you find that values which exist are still not being found, try increasing the number of steps

Constructor Summary

Constructors

Constructor and Description
DictionaryBinarySearch()

Method Summary

Methods

Modifier and Type	Method and Description
private static int	divergentSearch(java.lang.String value, java.lang.String[] sortedData, int idx, java.text.Collator c) Performs a divergent search which searches for the value in opposite directions from the index given, the number of steps in each direction to take is determined by the constant DIVERGENT_SEARCH_STEPS.
private static int	divergentSearch(java.lang.String value, java.lang.String[] sortedData, int idx, java.util.regex.Pattern p, java.text.Collator c) Performs a divergent search which searches for the value in opposite directions from the index given, the number of steps in each direction to take is determined by the constant DIVERGENT_SEARCH_STEPS.
private static int	multiLangSearch(java.lang.String value, java.lang.String[] sortedData, java.text.Collator c)
private static int	multiLangSearch(java.lang.String value, java.lang.String[] sortedData, java.util.regex.Pattern p, java.text.Collator c)
static int	search(java.lang.String value, java.lang.String[] sortedData, java.text.Collator c) Searches for the value specified and returns the index where the first instance of the value provided is found in the sorted array of data.
static int	search(java.lang.String value, java.lang.String[] sortedData, java.util.regex.Pattern p, java.text.Collator c) Searches for the value specified and returns the index where the first instance of the value provided is found in the sorted array of data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DIVERGENT_SEARCH_STEPS

private static final int DIVERGENT_SEARCH_STEPS

The number of steps to take when performing the divergent search, if you find that values which exist are still not being found, try increasing the number of steps

See Also:

Constant Field Values

Constructor Detail

DictionaryBinarySearch

public DictionaryBinarySearch()

Method Detail

search

public static int search(java.lang.String value,
         java.lang.String[] sortedData,
         java.text.Collator c)
                  throws java.lang.IllegalArgumentException

Searches for the value specified and returns the index where the first instance of the value provided is found in the sorted array of data. A custom variant of binary search is used, which is tailored to searching almost-sorted data, where the data is from multiple latin-based languages.

Parameters:

value - The value to search for in the sorted data provided

sortedData - The sorted data to search through

c - The comparator to use for performing comparisons

Returns:

The index of the first instance of the value in the data if found, -1 if the value is not found

Throws:

java.lang.IllegalArgumentException - If the data is not sorted or the value is null TODO Add support to check if the data provided is not sorted and throw an exception if it isn't

search

public static int search(java.lang.String value,
         java.lang.String[] sortedData,
         java.util.regex.Pattern p,
         java.text.Collator c)
                  throws java.lang.IllegalArgumentException

Searches for the value specified and returns the index where the first instance of the value provided is found in the sorted array of data. A custom variant of binary search is used, which is tailored to searching almost-sorted data, where the data is from multiple latin-based languages.

Parameters:

value - The value to search for in the sorted data provided

sortedData - The sorted data to search through

p - The pattern to refine searching for the value within the data

c - The comparator to use for performing comparisons

Returns:

The index of the first instance of the value in the data if found, -1 if the value is not found

Throws:

java.lang.IllegalArgumentException - If the data is not sorted or the value is null TODO Add support to check if the data provided is not sorted and throw an exception if it isn't

multiLangSearch

private static int multiLangSearch(java.lang.String value,
                  java.lang.String[] sortedData,
                  java.text.Collator c)

Parameters:

value - The value to search for in the sorted data provided

sortedData - The sorted data to search through

p - The pattern to refine searching for the value within the data

c - The comparator to use for performing comparisons

Returns:

The index of the first instance of the value in the data if found, -1 if the value is not found

See Also:

search(String, String[], Collator)

multiLangSearch

private static int multiLangSearch(java.lang.String value,
                  java.lang.String[] sortedData,
                  java.util.regex.Pattern p,
                  java.text.Collator c)

Parameters:

value - The value to search for in the sorted data provided

sortedData - The sorted data to search through

p - The pattern to refine searching for the value within the data

c - The comparator to use for performing comparisons

Returns:

The index of the first instance of the value in the data if found, -1 if the value is not found

See Also:

search(String, String[], Pattern, Collator)

divergentSearch

private static int divergentSearch(java.lang.String value,
                  java.lang.String[] sortedData,
                  int idx,
                  java.text.Collator c)

Performs a divergent search which searches for the value in opposite directions from the index given, the number of steps in each direction to take is determined by the constant DIVERGENT_SEARCH_STEPS. TODO There is probably some elegent way of determining the actual maximum value for step size to ensure that the value is always found

Parameters:

value - The value to search for in the sorted data provided

sortedData - The sorted data to search through

idx - The index to start the divergent search from

c - The comparator to use for performing comparisons

Returns:

The index of the first instance of the value in the data if found, -1 if the value is not found

divergentSearch

private static int divergentSearch(java.lang.String value,
                  java.lang.String[] sortedData,
                  int idx,
                  java.util.regex.Pattern p,
                  java.text.Collator c)

Performs a divergent search which searches for the value in opposite directions from the index given, the number of steps in each direction to take is determined by the constant DIVERGENT_SEARCH_STEPS. TODO There is probably some elegent way of determining the actual maximum value for step size to ensure that the value is always found

Parameters:

value - The value to search for in the sorted data provided

sortedData - The sorted data to search through

idx - The index to start the divergent search from

p - The pattern to refine searching for the value within the data

c - The comparator to use for performing comparisons

Returns:

The index of the first instance of the value in the data if found, -1 if the value is not found